Efficacy of lasalocid against murine Pneumocystis carinii pneumonitis.

The efficacy of the ionophore lasalocid against Pneumocystis carinii pneumonitis in corticosteroid-immunosuppressed Sprague-Dawley rats was investigated. Lasalocid was effective in the prevention of the pneumonitis in a dose-dependent manner. At dosages of 0, 5, 10, and 20 mg/kg/day, P. carinii infection rates were 92, 60, 20, and 0%, respectively, during dexamethasone immunosuppression. Also, lasalocid compared favorably with other drugs known to have anti-P. carinii activity, including trimethoprim-sulfamethoxazole, atovaquone, and dapsone-trimethoprim.